Oreo O's disappeared everywhere except for South Korea!

In 1998, Post Holdings launched a cereal called Oreo O's. As the name suggests, the cereal consisted of Oreo flavored o-shaped cereal. Delicious. Oreo O's was sold from 1998 until 2007. After that Post and Kraft were no longer co-branded. Kraft owned the right to the Oreo name, and Post owned the cereal recipe.

Thus, the world was denied it's Oreo O's - all except one place. South Korea. The cereal is still produced and available there because of a fortuitous turn of events. The Korean food company, Dongush Foods, was partially owned by General Foods. It was also licensed to sell Post products.

Kraft then purchased General Foods and half of Dongush's was then owned by Kraft. Hence, Dongush is the only company with both licenses - the right to the Oreo name and the actual cereal recipe - necessary to produce Oreo O's.

(Source)